Enhanced sensitization after cordocentesis in a rhesus-isoimmunized pregnancy.

It has been suggested that the optical density at 450 nm may be an unreliable predictor of the severity of fetal anemia in the midtrimester of pregnancy; therefore fetal blood sampling, rather than amniotic fluid evaluation, should be performed in all isoimmunized pregnancies with elevated maternal antibody titers in the midtrimester. Potential complications of such an approach are discussed and an alternative plan of management is offered.